Screening method for taxis of defoliators to coniferous trees

Abstract

The invention belongs to the technical field of resistance breeding, and particularly relates to a screening method for taxis of defoliators to coniferous trees. The method for screening the taxis of the defoliating pests to the coniferous trees comprises the following steps: cutting branches of coniferous trees of a reference strain, and carrying out water retention treatment on the cut parts of the branches; arranging the branches subjected to water retention treatment into a middle blank area, placing defoliating pests in the middle blank area, and observing the taxis of the defoliating pests to the branches. According to the screening method, the coniferous tree germplasm with high resistance to the defoliating pests can be screened out, so that the insect-resistant breeding of the coniferous trees becomes possible, the authenticity and stability of the resistance of the bred variety to the defoliating pests are ensured, and meanwhile, the time required for carrying out the insect-resistant breeding of the coniferous trees is also greatly shortened.

Description

Technical Field

[0001] The invention belongs to the technical field of resistance breeding, and in particular relates to a method for screening the tropism of leaf-feeding pests to coniferous trees. Background Art

[0002] The larvae of leaf-feeding pests of coniferous trees mainly feed on the needles of larch and other tree species. They can bite the needles into gaps, affecting the photosynthesis and growth rate of the coniferous trees. When the insect plague is serious, the leaf-feeding pests can eat all the needles, leaving the branches and trunks like they are on fire, causing the death of large areas of coniferous trees, seriously threatening the healthy development of forestry.

[0003] In forestry work, pest and disease problems and corresponding prevention and control strategies have become key issues of concern. The preference of insects for plants is the premise of damage. Therefore, screening and breeding insect-resistant strains can reduce the occurrence of pests and diseases at the source, and is an important content and link in pest and disease prevention and control. However, coniferous trees are generally tall, and it is difficult to investigate the insect resistance of different strains, which brings difficulties to the insect-resistant breeding of coniferous trees. In addition, the larvae of leaf-eating pests generally have a limited crawling distance, and it is almost impossible to conduct larval selection tropism experiments in the wild forest; the tropism selection of potted seedlings also needs to overcome various obstacles such as pots and soil. Therefore, how to conveniently evaluate the insect resistance of different varieties or strains of coniferous trees and realize convenient insect-resistant breeding of coniferous trees is imminent. Summary of the invention

[0004] In view of the above technical problems, the present invention provides a method for screening the tropism of leaf-feeding pests to coniferous trees. This method can be used to screen out coniferous tree germplasm with strong resistance to leaf-feeding pests, making coniferous tree insect-resistant breeding possible and ensuring the authenticity and stability of the resistance of the bred varieties to leaf-feeding pests. At the same time, it also greatly shortens the time required for carrying out coniferous tree insect-resistant breeding.

[0005] The technical solution of the present invention is as follows:

[0006] The invention provides a method for screening the tendency of leaf-eating pests to coniferous trees. The method comprises the following steps: cutting branches of reference coniferous trees, performing water-retention treatment on the cut parts of the branches; arranging the water-retention treated branches into a blank area in the middle, placing leaf-eating pests in the blank area in the middle, and observing the tendency of the leaf-eating pests to the branches.

[0007] In one embodiment, the water retention treatment is sealing in sterile water.

[0008] In one embodiment, the branches are placed in an observation box with uniform lighting.

[0009] In one embodiment, the branches of the reference coniferous tree are healthy seedlings free of eggs and / or larvae of leaf-feeding pests.

[0010] In one embodiment, the tropism is represented by the number of leaf-eating pests and the amount of feces within 48 hours.

[0011] In one embodiment, the spacing between the branches is not less than 3 cm.

[0012] In one embodiment, the length of the diagonal of the middle blank area is not less than 25 cm.

[0013] In one embodiment, the leaf-eating pests are placed at the intersection of the diagonals.

[0014] In one embodiment, the number of leaf-eating pests is more than 1.5 times the number of reference strains.

[0015] The present invention also provides an application of the screening method for the tropism of leaf-eating pests to coniferous trees in the breeding of coniferous tree insect resistance. Strains with fewer leaf-eating pests and less feces on the branches of the reference strains are selected for coniferous tree breeding.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] 1. The identification method of the present invention is simple and easy to implement, with low cost, little influence from environmental or human factors, strong operability, and can greatly shorten the time required for carrying out the breeding of coniferous tree insect resistance.

[0018] 2. The present invention makes it possible to breed coniferous tree germplasms with strong resistance to leaf-eating pests. By ensuring the authenticity and stability of the resistance of the bred varieties to leaf-eating pests through the number of leaf-eating pest larvae and the amount of feces on the branches, it solves the technical problem that it is difficult to investigate the insect resistance of different strains due to the tall shape of coniferous trees in reality. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a test diagram of larch branch treatment;

[0020] Figure 2 It is an effect diagram of larch branch treatment after 48 hours;

[0021] Figure 3 It is a selection experiment diagram of larch resistant to Dendrolimus superans larvae;

[0022] Figure 4 It is a selection result diagram of larch resistant to Dendrolimus superans larvae. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The present invention provides a screening method for the tropism of leaf-eating pests to coniferous trees. Cut the branches of the reference strains of coniferous trees and perform water retention treatment on the cut ends of the branches; arrange the branches with water retention treatment into an area with a blank middle, place leaf-eating pests in the middle blank area, and observe the tropism of the leaf-eating pests to the branches.

[0024] In the present invention, the length of the branches cut from the reference coniferous tree strains is not less than 15 cm, providing sufficient space for defoliating pests to gather on the branches of the same strain simultaneously, and meeting the natural selection of defoliating pests. As an implementation manner, the length of the branches is 15 cm - 25 cm. The present invention does not specifically limit the type of coniferous tree. As an implementation manner, the coniferous tree is one of coniferous trees such as Chinese pine, bunge pine, larch, cedar, Korean pine, Chinese arborvitae, Platycladus orientalis, Sabina chinensis, Spruce, Metasequoia glyptostroboides, Taxus chinensis, Araucaria cunninghamii, etc.

[0025] In the present invention, the water preservation treatment is to seal it in sterile water. Through the water preservation treatment of the shear part of the branches of the reference tree strains, different strains of larch can be kept fresh within 48 hours, avoiding interference with the selection of defoliating pests due to the drying of the branches of coniferous tree strains, and providing a prerequisite for the natural selection of defoliating pests for coniferous trees. As an implementation manner, the sealing is one of gasket sealing, packing sealing, and mechanical sealing; as an implementation manner, the sealing is film sealing.

[0026] In the present invention, the branches of the reference coniferous tree strains are healthy seedlings without defoliating pest egg masses and / or larvae. Selecting branches with larvae or egg masses will cause misjudgment of the screening results, and the branches of healthy seedlings can accurately and truly reflect the tropism of defoliating pests.

[0027] In the present invention, the branches are placed in an observation box with uniform illumination. Many kinds of insects have phototaxis and show a tendency towards light. In order to prevent the influence of light on the tropism of defoliating pests, the branches are set in an observation box with uniform illumination. As an implementation manner, the light source is set at the top of the observation box. As an implementation manner, the photoperiod is 14L:10D. In the present invention, there is no special limitation on the light intensity. In addition, defoliating pests need to live in a suitable environment and maintain normal metabolism within 48 hours. As an implementation manner, the temperature in the observation box is 15°C - 30°C, and in one implementation manner, the temperature is 20°C - 25°C; the humidity in the observation box is 40% - 90%, and in one implementation manner, the humidity is 50% - 70%.

[0028] In the present invention, the tropism is represented by the number of defoliating pests and the amount of feces within 48 hours. The number of defoliating pests on the branches of the reference tree strains can represent the degree of preference for the strains and directly reflect the tropism for coniferous tree strains; the amount of feces of defoliating pests can represent the degree of consumption of the strains and indirectly reflect the tropism for coniferous tree strains. The present invention makes a comprehensive judgment from two aspects of the number of pine caterpillars and the amount of feces, improving the authenticity and stability of larch insect-resistant breeding.

[0029] In the present invention, the spacing between the branches is not less than 3 cm, and the length of the diagonal of the middle blank area is not less than 25 cm. Coniferous trees secrete chemical signals such as plant volatiles and pheromones that affect the tropism of leaf-eating pests. By setting the spacing between the branches and the size of the middle blank area, the mutual interference of chemical signals between different strains can be avoided, and the tropism of leaf-eating pests can be truly reflected.

[0030] In the present invention, in order to reduce the interference of experimental factors, the leaf-eating pests are placed at the intersection of the diagonal of the middle blank area. As an implementation manner, the tips of the branches are arranged facing inwards. As an implementation manner, the blank area is one of a circle, a sector, an ellipse, and a polygon.

[0031] In the present invention, the number of the leaf-eating pests is more than 1.5 times the number of reference strains, so as to reduce the influence of too few leaf-eating pests on the screening result. As an implementation manner, the leaf-eating pests are one or more of pine caterpillars, sawflies, geometrid moths, and tortricids; in one implementation manner, the pine caterpillars include Dendrolimus punctatus, Dendrolimus tabulaeformis, and Dendrolimus superans; in one implementation manner, the sawflies include Diprion pini, Acantholyda posticalis, and Thrinaxodon thujae; in one implementation manner, the geometrid moths include Bupalus piniarius and Erannis ankeraria; in one implementation manner, the tortricids include Rhyacionia pinicolana and Cydia illutana. As an implementation manner, the leaf-eating pests are 3rd instar larvae.

[0032] The present invention also provides an application of the screening method for the tropism of the leaf-eating pests to coniferous trees in the breeding of coniferous tree insect resistance. Select the strains with fewer numbers of leaf-eating pests and less fecal amount on the branches of the reference strains for coniferous tree breeding.

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be described in detail below with reference to embodiments. However, they should not be construed as limiting the protection scope of the present invention.

[0034] For the materials, reagents, etc. used in the following embodiments, unless otherwise specified, the reagents, consumables, etc. involved in the present invention can be obtained from commercial channels. If the specific use conditions are not indicated, they are usually carried out under conventional conditions or according to the conditions recommended by the company.

[0035] Example 1 Pine Branch Water Treatment

[0036] Eight strains of larch that have been continuously used with uniform fertility, and consistent drainage and management are selected for insect resistance identification, with each plant as a replicate. The larch seedlings are managed according to the normal local cultivation level. A health census is conducted on the larch for resistance identification to ensure that there are no naturally occurring egg masses and larvae of Dendrolimus superans on the reference strains. If any are found, they are manually removed.

[0037] Cut pine branches with a length of 15 cm from each reference larch strain, insert the cut ends into centrifuge tubes containing sterile water, and seal them for water retention treatment. Then, in an observation box with a uniformly illuminated top light source, place the tips of the pine branches of 8 reference larch strains facing inward to form a circle with a blank area diameter of 25 cm. As Figure 1 shown, set the temperature in the observation box at 25 °C, the relative humidity at 50%, and the photoperiod at 14L:10D. Observe the withering and wilting of the pine branches of each strain at 24 hours, 48 hours, and 72 hours after the pine branches are placed. The results show that the pine branches of the 8 reference strains are relatively fresh after being placed for 24 hours; there is a slight wilting phenomenon in the pine branches after being placed for 48 hours, but there is still no dryness, as Figure 2 shown; the pine branches are dry and easy to fall off after being placed for 72 hours. The experimental results show that the water retention treatment method and the observation box environment of the present invention can keep different larch strains fresh within 48 hours, avoid interfering with the selection of Dendrolimus superans by the dryness of the pine branches of larch strains, and provide a prerequisite for the natural selection of Dendrolimus superans on coniferous trees.

[0038] Example 2

[0039] Collect 3rd instar larvae of Dendrolimus superans, and place the larvae of Dendrolimus superans in an artificial climate chamber at a temperature of (25±2) °C, a relative humidity of 50%±5%, and a photoperiod of 14L:10D for standby.

[0040] Select 20 larch strains that have been used continuously with uniform fertility, drainage and irrigation, and management for insect resistance identification, with each plant as a replicate. The larch seedlings are managed according to the normal local cultivation level. Conduct a health census on the larch for resistance identification to ensure that there are no naturally occurring egg masses and larvae of Dendrolimus superans on the reference strains. If any are found, remove them manually.

[0041] Cut pine branches with a length of 15 cm from 20 reference larch strains, insert the cut ends into centrifuge tubes containing sterile water, and seal them with a film for water retention treatment. Then, in the observation box, place the tips of the pine branches of the reference larch strains facing inward to form a circle with a blank area diameter of 30 cm and a strain interval of 3 cm. Place 30 larvae of Dendrolimus superans at the intersection of the diagonals of the blank area in the middle of the circle. After inoculating the insects, set the temperature in the observation box at 25 °C, the relative humidity at 50%, and the photoperiod at 14L:10D. To meet the natural selection of Dendrolimus superans on pine trees, investigate the selection of Dendrolimus superans larvae on the pine branches of each reference strain 48 hours later.

[0042] Example 3

[0043] Collect 3rd instar larvae of Bupalus piniarius, and place the larvae of Bupalus piniarius in an artificial climate chamber at a temperature of (20±2) °C, a relative humidity of 60%±5%, and a photoperiod of 14L:10D for standby.

[0044] Fifteen strains of spruce that have been used continuously for several years with uniform fertility, consistent irrigation and drainage, and management were selected for insect resistance identification, with each plant as a replicate. The spruce seedlings were managed according to the normal local cultivation level. A health census was conducted on the spruce for resistance identification to ensure that there were no naturally occurring egg masses and larvae of the spruce sawfly on the strains to be tested. If any were found, they were manually removed.

[0045] Cut branches of 20 cm in length from 15 strains of spruce to be tested, and insert the cut ends into centrifuge tubes containing sterile water. Seal them with a film for water treatment. Then, in the observation box, arrange the branches of the spruce strains to be tested with their tips facing inwards to form a circle with a blank area diameter of 35 cm and a strain interval of 5 cm. Place 30 spruce sawflies in the blank area in the middle of the circle. After infesting with insects, set the temperature in the observation box at 25 °C, the relative humidity at 50%, and the photoperiod at 14L:10D. To meet the natural selection of the spruce sawfly for spruce, investigate the selection of spruce sawfly larvae on the branches of each strain to be tested 48 hours later.

[0046] Example 4

[0047] Collect 3rd instar larvae of the Chinese juniper sawfly and place them in an artificial climate chamber at a temperature of (25 ± 2) °C, a relative humidity of 70% ± 5%, and a photoperiod of 14L:10D for standby.

[0048] Fifteen strains of Chinese juniper that have been used continuously for several years with uniform fertility, consistent irrigation and drainage, and management were selected for insect resistance identification, with each plant as a replicate. The Chinese juniper seedlings were managed according to the normal local cultivation level. A health census was conducted on the Chinese juniper for resistance identification to ensure that there were no naturally occurring egg masses and larvae of the Chinese juniper sawfly on the strains to be tested. If any were found, they were manually removed.

[0049] Cut branches of 25 cm in length from 15 strains of Chinese juniper to be tested, and insert the cut ends into centrifuge tubes containing sterile water. Seal them with a film for water treatment. Then, in the observation box, arrange the branches of the Chinese juniper strains to be tested with their tips facing inwards to form a square with a blank area diameter of 35 cm and a strain interval of 5 cm. Place 40 Chinese juniper sawflies in the blank area in the middle of the square. After infesting with insects, set the temperature in the observation box at 25 °C, the relative humidity at 50%, and the photoperiod at 14L:10D. To meet the natural selection of the Chinese juniper sawfly for Chinese juniper, investigate the selection of Chinese juniper sawfly larvae on the branches of each strain to be tested 48 hours later.

[0050] Example 5 Tropism test of the larch caterpillar on 20 strain materials

[0051] Repeat the experiment of Example 2 with the same experimental protocol in 2 different observation boxes. The selection process is as Figure 3 shown, and the selection results of larch resistant to larch caterpillar larvae 48 hours later are as Figure 4 and Table 1 shown:

[0052] Table 1 Selection Results of Larch Resistance to Dendrolimus superans Larvae

[0053]

[0054] Table 2 Larch Resistance Evaluation Criteria

[0055]

[0056] Note: The proportion of selected individuals = the number of selected individuals / the total number of effective selected individuals * 100%, and the total number of effective selected individuals is the total number of individuals on the selected reference strains.

[0057] As can be seen from Table 1 above, after 2 repetitions, a total of 35 insects climbed onto the pine branches of 17 larch reference strains. However, there were different numbers of Dendrolimus superans on the pine branches of strains 48 - 261, X5*X9, 48 - 129, 48 - 649, and C7604, but there was no feces produced by Dendrolimus superans after eating the pine branches; there were no Dendrolimus superans on the pine branches of strain 48 - 155, but there was 0.0256 g of feces produced by Dendrolimus superans after eating the pine branches; only on the pine branches of two larch strains, 47 - 764 and S264, there were neither Dendrolimus superans nor feces of Dendrolimus superans. Combining with the evaluation criteria in Table 2, the experimental results show that larch strains 50 - 327, R5*C78 - 3, and S401 have strong attractiveness to Dendrolimus superans, strain 48 - 155 has weak attractiveness to Dendrolimus superans, strains 47 - 764 and S264 have no attractiveness to Dendrolimus superans, and the remaining 14 larch strains have moderate attractiveness to Dendrolimus superans. The insect - resistance breeding screening method of the present invention can achieve the effect of differentiating attractiveness, and can comprehensively consider the number of Dendrolimus superans and the amount of feces to improve the authenticity and stability of larch insect - resistance breeding. The screening method of the present invention can screen out coniferous tree germplasms with strong resistance to leaf - eating pests, make coniferous tree insect - resistance breeding possible, ensure the authenticity and stability of the resistance of the bred varieties to leaf - eating pests, and at the same time greatly shorten the time required for carrying out coniferous tree insect - resistance breeding.

[0058] The above - mentioned are only embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made using the content of the specification of the present invention, or directly or indirectly applied in other related technical fields, shall be included in the patent protection scope of the present invention by the same token.

Claims

1. A method for screening the tropism of leaf-feeding pests to coniferous trees, characterized in that: The following steps are involved: Cut the branches of coniferous trees of the reference variety and perform water conservation treatment on the cut parts of the branches; The branches treated with water retention are arranged to form a blank area in the middle, and leaf-feeding pests are placed in the blank area in the middle to observe the tendency of the leaf-feeding pests to the branches.

2. The method for screening the tropism of leaf-feeding pests to coniferous trees according to claim 1, characterized in that: The water retention treatment is sealing in sterile water.

3. The method for screening the tropism of leaf-feeding pests to coniferous trees according to claim 1, characterized in that: The branches are placed in an observation box with uniform lighting.

4. The method for screening the tropism of leaf-feeding pests to coniferous trees according to claim 1, characterized in that: The branches of the coniferous trees of the reference strain are healthy seedlings free of eggs and / or larvae of leaf-eating pests.

5. The method for screening the tropism of leaf-feeding pests to coniferous trees according to claim 1, characterized in that: The tendency is expressed by the number of leaf-feeding pests and the amount of feces within 48 hours.

6. The method for screening the tropism of leaf-feeding pests to coniferous trees according to claim 1, characterized in that: The branches are arranged at a distance of not less than 3 cm.

7. The method for screening the tropism of leaf-feeding pests to coniferous trees according to claim 1, characterized in that: The diagonal length of the middle blank area is not less than 25 cm.

8. The method for screening the tropism of leaf-feeding pests to coniferous trees according to claim 7, characterized in that: The leaf-feeding pests are placed at the intersection of the diagonal lines.

9. The method for screening the tropism of leaf-feeding pests to coniferous trees according to claim 1, characterized in that: The number of the leaf-eating pests was 1.5 times greater than that of the reference strains.

10. Use of the method for screening the tropism of leaf-feeding pests to conifers according to any one of claims 1 to 9 in breeding conifers for insect resistance, characterized in that: Select reference strains with fewer leaf-feeding pests on their branches and less feces for conifer breeding.

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